Electrocatalytic nitrate reduction to hydroxylamine (ENRH) provides a sustainable strategy for NH₂OH synthesis under ambient conditions. At present, active hydrogen (*H) derived from water dissociation has been widely used as a H-source for nitrate hydrogenation, bringing a big challenge for ENRH. On the one hand, insufficient *H would lead to the accumulation of nitrite. On the other hand, sufficient *H with high reduction ability would induce over-hydrogenation of hydroxylamine to ammonia. To overcome this challenge, herein, we propose to utilize lattice hydrogen (H_lat) with an appropriate reduction ability as the H-source for ENRH. We design and construct a Cu-MnO₂H _x electrocatalyst, in which the Cu-triggered Jahn–Teller distortion of [MnO₆] octahedron significantly increases the number of H_lat. The Faradaic efficiency and yield of NH₂OH are as high as 91.1% and 396.6 mmol g_cat. ^–1 h^–1 over Cu-MnO₂H _x , outperforming most of the reported catalysts. The combined results of isotopic tracking experiments and theoretical calculations prove the enrichment and buffer functions of H_lat, which can provide an abundant H-source for nitrate’s selective reduction to hydroxylamine.

中文翻译：

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晶格氢涉及电催化硝酸盐还原为羟胺

电催化硝酸盐还原成羟胺 （ENRH） 为环境条件下的 NH₂OH 合成提供了一种可持续的策略。目前，水解离得到的活性氢 （*H） 已被广泛用作硝酸盐加氢的 H 源，给 ENRH 带来了很大的挑战。一方面，不足的 *H 会导致亚硝酸盐的积累。另一方面，具有高还原能力的足够 *H 会诱导羟胺过度氢化为氨。为了克服这一挑战，本文建议使用具有适当还原能力的晶格氢 （H_lat） 作为 ENRH 的 H 源。我们设计并构建了一种 Cu-MnO₂H _x 电催化剂，其中 Cu 触发的 [MnO₆] 八面体的 Jahn-Teller 畸变显着增加了 H_lat 的数量。NH₂OH 的法拉第效率和产率高达 91.1% 和 396.6 mmol g_cat。^-1 h^–1 比 Cu-MnO _{高 2}H _x ，性能优于大多数已报道的催化剂。同位素跟踪实验和理论计算的综合结果证明了 H_lat 的富集和缓冲功能，可为硝酸盐选择性还原为羟胺提供丰富的 H 源。